Been using a pair for a few years now.. absolutely love them. They are a little bit of a faff to get setup as the cleat basically is the pedal.. all the retention mechanism is in the cleat. The most common problem with people getting clipped in and out is that they have over tightened the cleat plate when fitting, it has a detent on the screws and it's basically snugged up plus one click or the cleat will be too tight and the spring can't release. Other than that they are easier to get into than single sided as you just stomp on them like SPD's.
Would definitely recommend cleat covers too as one step in soft ground can foul the cleat and make it impossible to clip in, not a problem if you are the type that goes out riding rather than takes their bike for a walk.!!
The only other thing to consider is that the float on them is unsprung, this basically means that your foot is free to float around on the pedal which feels very weird to start with, especially out of the saddle, I got used to it quite quickly, YMMV.